A Buggy had a large engine but very little armor - to the point where the person inside was almost completely exposed to outside fire. It did have more armor than the even more thin-hulled Recon Bike, but this could not protect it against any serious threats. The M-60 machine gun was effective against infantry and very light vehicles, but was very inefficient against heavily armored vehicles. It was succeeded by a very similar unit, the Attack Buggy.
Nod Buggies were used as scouts, and for anti-infantry work, often accompanying a group of tanks. Although their lack of armor made them vulnerable to some units, they were also cheap - even cheaper than the equivalent GDI Humvee. This meant Nod commanders were willing to use them in situations from which they might not return, and they were used very heavily as patrol units. As a very low tech and inexpensive unit, they were deployed in nearly every engagement Nod fought in during the First Tiberium War.
Against heavy anti-tank weapons such as Medium Tanks, the buggy would be destroyed Its lack of an anti-armor weapon as well as its thin armor plating made it extremely vulnerable to heavy armor. Therefore, it would take a very large amount of Buggies to successfully destroy a Mammoth tank. In addition, these characteristics made them also fare very poorly against GDI base defenses. Advanced Guard Towers in particular were highly effective, owing to the lack of armor and ineffective weaponry.